The present invention relates to a pressure relief valve for a packaging container with significantly improved sealing properties.
Various embodiments of pressure relief valves for packaging containers are known from the prior art. The use of valves, especially on flexible packages for foodstuffs, has already been implemented by a large number of technical variants. A principal requirement on valves of this kind is that they should permit only slight excess pressures in the package through appropriate opening and otherwise should reliably prevent the penetration of ambient air. In this context, the penetration of ambient air must be prevented even when the pressure in the package is very low. In practice, however, the two above-mentioned aims are in conflict since, on the one hand, the pressure for opening the valve should only be low and, on the other hand, high vacuum tightness should be provided. Valves which have a high vacuum tightness therefore also have a very high opening pressure. In contrast, valves with only a low opening pressure do not have the necessary vacuum tightness.
EP 1 802 537 B1 has disclosed a pressure relief valve which is designed to be uneven in part in a recess in a main body. This results in differences in the distance between the recess and a valve diaphragm in different zones. This valve has fundamentally proven its worth but very recently there have been an increasing number of uses which require an improved opening characteristic and vacuum tightness.